Naim ND5 XS: the new Naim XS series network player

15 September 2011. Milan Italy. Naim today launched the ND5 XS: Naim’s first network player to stream 24bit/192kHz sources natively. Designed and engineered to integrate into Naim’s range at a similar quality level as Naim’s slimline XS series, the ND5 XS is performance upgradeable in stages as the owner demands. The ND5 XS is performance upgradeable currently by the addition of a XPS or PS 555 power supply and/or Naim DAC. A matching slimline power supply will be available next year

nd5xs_rear

The ND5 XS is a network player designed to match Naim’s XS series products. Naim envisages the owners of the ND5 XS using it, primarily, as a high-end quality streamer playing back music ripped from CDs or hi-res music downloaded from the many online stores.

Technically, the ND5 XS draws significantly from the hugely successful Naim DAC and Naim NDX. The innovative and SHARC DSP-based buffering with fixed clocks is utilised along with 16 times oversampling and Naim’s proprietary, low-generated noise, digital filtering algorithms.

The ND5 XS adds far more to a system than just streaming. It includes three S/PDIF digital inputs to support connection from computers, to set top boxes, to CD players.

It includes internet radio – the radio of the future –supported by vTuner’s five star full service. Search for stations by genre, location or just simply by name. New stations are added automatically to the searchable database. Add special favourites or less common feeds to ‘added stations’ via Naim’s internet radio webpage. Also included is Naim’s Choice delivering Naim-recommended stations including exclusive higher quality radio streams.

Apple authentication enables digital connection of iPhone, iPad and iPod allowing the ND5 XS to play all stored music, podcasts or audiobooks. Play music on a USB stick, even those containing hi-resolution WAV or FLAC files, with full on-screen control.

Control the ND5 XS with the front-panel buttons, the supplied remote control or an iPhone, iPad or iPod Touch running the FOC n-Stream app. The app also enables System Automation; allowing control of a Naim system’s inputs and volume.

Choose the optional FM/DAB module to add terrestrial radio stations. Maybe your favourite radio station has yet to start its internet radio stream.

Key Features

UPnPTM Network Player for sources up to 24bit/192kHz sampling (includes 32Bit Floating Point)

Linear power supply — Large toroidal transformer with four secondary outputs.

Separate power supplies for digital, analogue, DSP and clock

Performance upgradeable with XPS or 555 PS power supply

Performance upgradeable with Naim DAC

Ground selector switch for optimum performance

Naim low-profile non-magnetic, low-resonance low microphony case

OLED display for high contrast and easy visibility

British design and build

Background

Just over three years ago, when Naim launched the innovative HDX hard disk player there was a shortage of streaming players and a real dearth of DACs. Now, there is no longer a shortage of either of these but there is still a significant shortage of players that deliver a true musical performance and not just shiny Hi-Fi sound.

Delivering music over Ethernet or Wi-Fi is not difficult, but to do it really well requires an attention to detail that is still surprisingly rare in today’s market.

It requires control over every part of the chain possible. CD rips have to be undertaken correctly – a CD rip must be a secure rip. Storage needs to be fast, reliable (and of course backed up). The network needs to be well set up, with low collisions, and plenty of bandwidth.

Finally the player should be designed to be low jitter, reject the RF and other aberrations from noisy power supplies, mobile phones, the general environment and of course the EMI from computers. This is in addition to the standard audio requirements of technically measuring well, having a well-designed and hence good low-impedance power supply and good choice of components.

These are the basic building blocks. Then the attention to detail really counts.

Technical

The ND5 XS has galvanic isolation between key sections of the circuits. This reduces the noise transfer to the analogue domain from the digital circuits and connections. Whether the ND5 XS is playing from internal or external digital sources, the digital data is isolated from the DSP and in turn, the DSP is isolated from the master clock and DAC. There is maximum isolation between digital sources and analogue output. The power supplies for each section of the signal path are also independent. Four separate secondary windings feed four separate power supplies for isolation.

Naim’s buffer or memory method of jitter removal relies on a simple concept: the audio data clocks into the memory at the incoming inconsistently timed rate and then a precise clock controls the data out of the memory and into the DAC chips. Selecting the master clock that best matches the average incoming clock frequency, controls the rate at which the memory fills and empties. In this way, the data entering the DAC chips is completely isolated from the incoming jitter.

The ND5 XS uses the same 16 times oversampling filter as the Naim DAC, implemented in the SHARC processor. The chosen filter is a modified Butterworth filter to which additional poles are added to prevent too much phase shift occurring within the audio band. The filter runs as efficiently as possible, using only five lines of assembly code. This ensures both low arithmetic noise (fewer additions and multiplications that cause rounding) and low power supply noise.

The DAC in the ND5 XS is a Burr Brown PCM1791A. It is used in 16 times external oversampling mode and runs at a maximum sample rate of 768 kHz.

The analogue output filter is multi-stage seven-pole filter. The design uses Burr Brown OPA604 opamps to perform the filtering; these are single chip opamps so a total of six are required. There is a plethora of audio opamps available but for the ND5 XS, the OPA604 delivered. A combination of Sallen-Key and multiple feedback low pass filters are used to implement the seven-pole filter.

Reducing power supply (PSU) noise has long been part of Naim’s design philosophy. To increase perceived and measured dynamic range, PSU noise in the ND5 XS is reduced to an extremely low level.

The ND5 XS can be powered from its internal (integrated) power supply or as an upgrade an external Naim power supply; XPS (Classic Series model only) or 555 PS. A matching slimline power supply will be launched next year.

The reservoir capacitors are larger than would typically be used to reduce the unregulated voltage noise and provide increased short-term current capability. The four separate power supplies form part of the electrical isolation of the Digital DSP section from the DAC chips and analogue circuits.

Low noise LM317/337 regulators smooth the unregulated voltage from the reservoir capacitors. Voltage supplies to many of the digital circuits are double and in some cases triple regulated to further reduce noise. Quadruple regulated if using an external supply.

When an external power supply upgrade is used with the ND5 XS, power supply separation is maintained as the external power supply also has independent power supplies and ground connections. It also provides a significantly larger toroidal transformer and larger reservoir capacitors to further noise reduction.

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